Embodiments of the present apparatus and method relate generally to the ultraviolet treatment of a substrate.
In the manufacture of integrated circuits, displays, and solar panels, layers of dielectric, semiconducting, and conducting materials are formed on a substrate such as a semiconductor wafer, glass panel or metal panel. These layers are then processed to form features such as electrical interconnects, dielectric layers, gates and electrodes. In other processes, ultraviolet radiation can be used to treat the layers or features formed on the substrate. For example, ultraviolet radiation can be used in rapid thermal processing (RTP) to rapidly heat a layer formed on the substrate. Ultraviolet radiation is also used to promote condensation and polymerization of polymeric layers. Ultraviolet radiation can also be used to generate stressed film layers. Ultraviolet radiation can also be used to activate gases to clean a chamber.
In one application, ultraviolet (UV) radiation is used to treat films of silicon oxide, silicon carbide, or carbon-doped silicon oxide. For example, commonly assigned U.S. Pat. Nos. 6,566,278 and 6,614,181, both incorporated by reference herein and in their entireties, describe the use of ultraviolet light for the treatment of silicon-oxygen-carbon films. Materials such as silicon oxide (SiOx), silicon carbide (SiC), and silicon-oxygen-carbon (SiOCx) films are used as dielectric layers in the fabrication of semiconductor devices. Chemical vapor deposition (CVD) methods are often used to deposit these films, and involve promoting a thermal or plasma based reaction between a silicon supplying source and an oxygen supplying source in a CVD chamber. In some of these processes, water can be formed as a by-product of the CVD or other reaction. For example, water can be formed in the deposition of silicon-oxygen-carbon or silicon carbide films by CVD processes that use an organosilane source which includes at least one Si—C bond. The process-generated water can be physically absorbed into the films as moisture or incorporated into the deposited film as Si—OH chemical bond, both of which are undesirable.
Ultraviolet radiation can be used to treat these films to cure and densify the deposited CVD film. Advantageously, ultraviolet treatment reduces the overall thermal budget of an individual wafer and speeds up the fabrication process. A number of ultraviolet curing chambers have been developed which can be used to effectively cure films deposited on substrates 38, such as, for example, U.S. application Ser. No. 11/124,908, filed May 9, 2005, and published as Patent Application Publication No. US 2006/0251827 A1 entitled “Tandem UV Chamber for Curing Dielectric Materials” which is assigned to Applied Materials, Inc., of Santa Clara, Calif. and incorporated by reference herein and in its entirety. In such ultraviolet processes, it is desirable to increase the intensity of the ultraviolet radiation to provide faster curing times and shorter process cycles. However, increasing the ultraviolet radiation by using high-power sources or other means also increases the heat generated within the chamber. This excessive heat can have adverse effects on the features being processed on the substrates and can also shorten the life of the ultraviolet sources themselves.
For reasons including these and other deficiencies, and despite the development of various UV curing chambers and techniques, further improvements in ultraviolet treatment technology are continuously being sought.